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Message-ID: <be2b2dfc-ed6c-f762-7e4c-9d22b13717fe@bell.net>
Date:   Tue, 10 Jan 2023 03:06:53 -0500
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From:   Matt Fagnani <matt.fagnani@bell.net>
Subject: =?UTF-8?Q?Re=3A_=5Bregression=2C_bisected=2C_pci/iommu=5D_Bug=C2=A0?=
 =?UTF-8?Q?216865_-_Black_screen_when_amdgpu_started_during_6=2E2-rc1_boot_w?=
 =?UTF-8?Q?ith_AMD_IOMMU_enabled?=
To:     Baolu Lu <baolu.lu@linux.intel.com>,
        Jason Gunthorpe <jgg@nvidia.com>,
        Vasant Hegde <vasant.hegde@amd.com>
Cc:     Thorsten Leemhuis <regressions@leemhuis.info>,
        Joerg Roedel <jroedel@suse.de>,
        "iommu@lists.linux.dev" <iommu@lists.linux.dev>,
        LKML <linux-kernel@vger.kernel.org>,
        "regressions@lists.linux.dev" <regressions@lists.linux.dev>,
        Linux PCI <linux-pci@vger.kernel.org>,
        Bjorn Helgaas <bhelgaas@google.com>
References: <15d0f9ff-2a56-b3e9-5b45-e6b23300ae3b@leemhuis.info>
 <5aa0e698-f715-0481-36e5-46505024ebc1@bell.net>
 <aea57c5f-2d20-c589-ad44-a63f1133a3db@linux.intel.com>
 <157c4ca4-370a-5d7e-fe32-c64d934f6979@amd.com>
 <223ee6d6-70ea-1d53-8bc2-2d22201d8dde@bell.net>
 <6fff9d10-f77f-e55a-9020-8a1bd34cf508@amd.com> <Y7gs0zYKp/VXACBi@nvidia.com>
 <f96b1cf3-6865-663d-f1cd-466a71519b08@linux.intel.com>
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Baolu,

I tried to apply your patch after checking out 6.2-rc3 and origin/master 
but there were there the following errors.

git apply amd-iommu-amdgpu-boot-crash-2.patch
error: patch failed: drivers/pci/ats.c:382
error: drivers/pci/ats.c: patch does not apply

I manually changed drivers/pci/ats.c as shown in the patch. I built 
6.2-rc3 + the patch. 6.2-rc3 with the patch had the same black screen 
problem when booting. I added rd.driver.blacklist=amdgpu on the kernel 
command line to prevent amdgpu from being started while the initramfs 
was in use, and the black screen happened later in the boot as I 
described in my previous email. The journal showed the same two warnings 
and null pointer dereference which made amdgpu crash as I reported.

Thanks,

Matt